As detective drama Scott & Bailey returns to ITV for its fourth series (premieres Wednesday, Sept 10), Rachel’s got her eye on the sergeant’s job, as Suranne Jones reveals…

We know that this series of Scott & Bailey begins with Rachel and Janet (Lesley Sharp, left) vying for the job of sergeant. What does being a sergeant mean to Rachel?

“Rachel knows she’s made mistakes, but she’s decided to sort herself out and mature and she’s positive she can do it. She’s getting divorced from husband Sean and sees a promotion as an exciting new start.”

Rachel and Janet fell out big time last series after Janet caught Rachel sleeping with colleague Kevin in her spare room and threw her out. They eventually made up – but what’s their friendship like now?

“Rachel and Janet’s friendship really did hit rock bottom so, while they are friends again, they don’t tell each other everything that, once upon a time, they would have.”

So what impact does competing for the promotion have on their friendship?

“Rachel and Janet are happy working together, but they also have an ulterior motive of having to prove themselves – they both have their eye on the prize. Work-wise, their relationship will be fiery, whoever gets the job.”

Do you think viewers like to see Rachel and Janet getting on?

“Lesley and I are very aware if we’re filming a scene where there’s supposed to be ‘banter’ or ‘bickering’ between Rachel and Janet that things don’t become too fractious. We know viewers don’t want to see two women battling because that’s never been what Scott & Bailey is about.”

The last series followed a ‘House of horrors’ story arc. Would you say this series is as ‘dark’ as the last one?

“I’d say the first three episodes are introducing us back into police life and the last three do get pretty grim. But you never really see blood and guts on this show – it’s more about what Rachel and Janet say.”

Amelia Bullmore – the show’s DCI Gill Murray – has taken over much of the writing duties on this series from Sally Wainwright. What’s it like having Amelia on set as both an actress and writer?

“Amelia writes for the characters of Rachel and Janet brilliantly and it’s great having her on set. One minute she’s acting as Gill, then she takes her glasses off, goes all posh and says: ‘What do you mean, darling?’ It’s just a good atmosphere.”

Do you think Rachel’s changed at all over four series? Has she grown up?

“Yeah, definitely! In the first series she had men trouble, in the second series she had drink trouble and in the third series she had a terrible marriage and a wayward mother and brother! I thought that if we were to do a fourth series you couldn’t have a character that continues to be at odds with herself and her past. So she has grown up – she’s just still a bit immature.”

Did you worry Rachel would become really dislikeable?

“Well, I think people can understand why she is the way she is. I think that she is good at her job and she does have a good heart – but maybe it’s because I play her that I’m like: ‘She’s good really!'”

What do you still enjoy about playing Rachel after four series?

“I love that she’s this maverick cop, who’s a bit blokey and not afraid to get stuck in – but, unlike her, I’d say I’ve grown up!”